Various types of such roll-off pistons are known. On the one hand, there are relatively heavy roll-off pistons made of steel sheet with a fully usable interior volume and with an end stop, that is, a “buffer support”, namely a support for a stop buffer acting substantially in an axial direction of the air spring. The steel sheet roll-off piston is produced as a deep drawn part with a conical sealing seat for the flexible member receptacle and has a welded-in base part with a welded-on supporting tube. Although a piston of this kind with a buffer support made of steel sheet has sufficient stability to accept even relatively high loads or even, for emergency running, to accept bottoming of the vehicle body, the overall component is correspondingly heavy and expensive to produce.
On the other hand, there are relatively light one-piece plastic pistons. For reasons of weight saving, such plastic pistons are now also preferred by manufacturers of trucks. In terms of the load-carrying capacity of the buffer support, however, even pistons produced from glass fiber reinforced plastic can hardly reach the values for strength, endurance and temperature stability of buffer supports in the case of steel pistons. Moreover, for precisely these reasons, the interior volume of plastic pistons cannot be used or cannot be used to the full. Where it is not possible to use the interior volume or where it can only be used partially, however, such designs have a loss of comfort as a disadvantage. The springing is then relatively hard.
The alternatives in the prior art are then two-part plastic pistons with a usable interior volume but without a buffer support, in which the overall design of the chassis must then be reconfigured in such a way that the missing buffer support is replaced by other measures. An air spring piston of this kind is disclosed by EP 1 862 335 B1, for example. There, the air spring piston consists of a cup-shaped part and of a covering part, which are butt-welded together in the region of the walls thereof. Here, the cup-shaped part has a base wall which has an insert for connection to the vehicle axle. The disadvantage here is, as explained, the lack of an end stop (buffer support).
United States patent application publication 2010/0127438 also discloses a plunge piston designed as a hollow body for an air spring, consisting of two parts connected airtightly to one another, namely of a pot-shaped bottom part with a base and shell and of a top part. Here too, there is no end stop provided.